The broad, long-term goal of this work is to improve the diagnosis and treatment of patients with neurovascular disease. The diagnosis and treatment planning of often require the used of catheter- based x-ray angiography (XRA). Catheter angiography is the current referenced standard for intracranial angiography but exposes both the patients and physicians to high doses of radiation, requires an arterial puncture, the injection of nephrotoxic contrast agents and carries a slight risk of stroke. The use of intra-arterial catheters for XRA requires a hospital stay for recovery, adding to the cost of patient care. Magnetic Resonance Imaging (MRI) based angiographic images are widely available, and have reduced the use of XRA for the diagnosis of vascular disease in many vascular beds. However, due to the need of high frame images (up to 6 frames/sec) to capture bolus dynamics, XRA is still routinely performed to image the intracranial vasculature. We are developing an MRI-bases alternative to intracranial XRA based on using radial sampling and sliding window reconstruction. The minimally invasive nature of MR angiography will reduce the risk to patients undergoing diagnostic imaging of the brain. Using our approach to MR angiography can reach the frames and spatial resolution needed to capture the bolus dynamics that are normally observed with more invasive XRA. In the proposed work, we will implement our pulse sequence, validate the pulse sequence in phantoms, healthy normal subject, and in direct comparison with XRA in patients. We will test the following hypotheses: Specific Aim 1: We hypothesize that sliding window radial MRA can better depict flow dynamics than traditional block-wise MRI acquisitions. Specific Aim 2: We hypothesize that constrain reconstruction of radial sliding window images acquisition will improve the depiction of intracranial blood vessels without altering the imaging of flow dynamics. Specific Aim 3: We hypothesize that sliding window radial MRA can accurately depict the vasculature abnormalities in patients. Upon successful completion of this project we will have developed and validated a non-invasive adjunct to intracranial X-ray angiography We propose to develop an MRI-based imaging protocol for no-invasive imaging of the intracranial vasculature. Our goal is to develop a pulse sequence that can aid in the diagnosis and treatment planning of a wide range of neurovascular diseases. The current approach to this problem is catheter- based x-ray angiography which is invasive, carries a definite risk of stroke and subjects both patients and physicians to ionizing radiation. The successful completion of this project will results in fewer invasive imaging procedures being performed, resulting reduced risk to patients.